The field of orthodontics is a highly developed one which continues to seek improvements as better materials and techniques become available. Because of the increased cost of medical services, it becomes more important that the orthodontic bands be provided which can be applied to the patient's teeth by technicians without the assistance of the doctor. However, for this to be done, the appliances must be made in such a way that they are simply and correctly applied. A common problem with bands now available is that they are commonly misfitted on molars and bicuspid teeth wherein the band tips beyond the mesial ridge of the tooth. The band is stopped from moving downward on the mesial side because it wedges at the mesial contact point or stops because of mesial tissue resistance. If this misalignment of the band goes undetected by the doctor or staff, it eventually causes mechanical problems that can only be corrected by rebanding, which results in the loss of treatment time. In addition, two major problems are created. First, the roots of the tooth are kicked forward mesially in the alveolar bone crypt. Also, the mesial marginal ridge and crown is forced too far above the normal occlusal plane unfavorably affecting occlusion. The over eruption of the molar then can cause opening of the bite and premature contacts during treatment. This can create major problems in open-bite cases which are hard enough to treat when bands are properly placed.
Additionally, the great use of pre-welded attachments makes exact placement of the bands even more critical. This is true, because the welded attachments are attached to the band in a position which assumes that the band will be properly installed on the tooth. However, if the mesial side of the band slides downwardly beyond the crown, the welded attachments will be at an improper angle thereby adding to the difficulty in properly correcting tooth alignment. In order to provide proper band alignment, various band constructions have been developed, such as those shown in Myerson U.S. Pat. No. 1,884,128 and Kesling U.S. Pat. No. 3,990,151. Each of these bands are suitable for their intended purpose, they require a skilled doctor to install them properly.
Preformed bands such as that shown in Miller U.S. Pat. No. 3,513,545 is intended to provide a better fit. It has portions along the distal and mesial side which are thinner in cross-section and it is contoured to proximate the shape of a molar with the intent of obtaining a better fit.
Wolfson U.S. Pat. No. 4,192,068 discloses a band with a plurality of rests spaced around its perimeter for use with a tool for positioning the band on a tooth.
Although the prior art devices have experienced some success, they each require the skill of the doctor for installation and none of them recognize the requirement of the anatomy of a molar and bicuspid which results in the problem of the mesial side of the band sliding down too far toward the gingival tissue. The anatomy of the tooth which creates this problem is the fact that the distal side of the crown has a curved or bulbus shape whereas the mesial side of the crown is straighter. Thus, when a band is placed over the tooth, the distal side of the crown of the tooth because of its shape generally prevents the band from sliding too far down. However, since the mesial side has a straighter configuration, there is nothing to prohibit the band from moving down until it becomes wedged on the crown or is stopped by engagement with the gingival tissue. This can cause undesirable forces to be applied to a molar or bicuspid, adding to the problems of straightening the teeth.